SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8eac038ca49c46ec35a30d784f772779abdde2fca78ba1ea0470ba5af6950a7' 
  AND token = '9Fgg5I/bgKP77ETbw9w/ouzRKufrHrmMgQfnCcS9vw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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