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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18d2e49b72a01d1d20cf49b4dbffcd9051b9c2d5da52f2c5f50447e8e6a860d2' 
  AND token = 'ePDdb9Oz2O3Nlq3hSD5sNLBWpERNeMuL60p7bpETQnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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