SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db2fcd7dedfd11293dc6ad9a1f4a61671336590e4316d9f1b0f66a31403d2540' 
  AND token = 'NHrJFSH27LKF0MzQlWKZQQ9xnntei1pl/oLbJyIGjU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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