SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79b74b90fc472196301371a96d758966980970fe9a2241dede254e33e6f3ad72' 
  AND token = 'oOK//BDdtlhOkvCqSDv/78X4Ds8j+0DUuV7VwAimgmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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