SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c2b003618373746e684e9426933f1b2ac959618a6596ae541e505e044047bd9' 
  AND token = 'yYb5PuYCr0rdSTezH/HKe/3RvyFlWlmPflTRqguyMsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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