SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75bc9f8db20fc888243e3e7a4f3b29efa04691cf29bab9aeefd2d2be6f310915' 
  AND token = 'UUCaEyJQevdFlBzYB5n5EcW8onP/TU7oAB/FkI/wo7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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