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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b051bb24edc3e70f1e3f30323e52a4a5f21724ce60942b3bffc4943cd5e5871' 
  AND token = 'O7KTEiMDsXqwCHTa5FkOCGtOsySKmEs/aeQcOqGnKsM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}