SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c72b59c274e6764eebde6018612357b063956ed6722426762b92893f724d8c' 
  AND token = 'atf79RNS6zwQVVEb5ZZqolx2AYHFrhNvZlPm6/T+jJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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