SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6947d9be7b6e83250fc1d1ddda40e349d425b81bb5db132d4684a31d5eca923' 
  AND token = 'JvnhGMqL3jYojq1/QpVCX+eLHmDSjr7D3n+tGiGzwVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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