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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a7ec7848dde798deaf5eb08a65b61c9b994d5c8606bd0da9213d2e9c1db73ba' 
  AND token = 'HsiX3nIJVqUQC7uDXHvBV3wbn2CHmO38h1cvb8SF0Mg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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