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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce748c7cd4a59747982497bd53812ca1c68feca2c892c5bde0a59adccb2834e2' 
  AND token = 'r3MkrwxZzv7PwFDO6MLM75F0drwHFAXBQFgg6m52wfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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