SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eeb88290abc693b04290817551bce067d0ecdec461bd8dc2997f12aa9f56c7be' 
  AND token = '/kih1HidG8eQHcU6UZLfD1bKwTeF6veXgIUqaNEFqpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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