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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1a1601aefda91039f40c0664f5c1adcb94e503b5d79dcb5e6a3b3bdff104d40' 
  AND token = 'RWpKuFxZtaZqkXrBZ5M98hn/RdR81+lrsDz69eAJHvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}