SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ed8b15397e73a1a3aaf93968f441b64d30a33bb93c92d54dc1ffce9250a7d12' 
  AND token = 'bzkg2cYit20EJ+y9+j6irQuGsnH83qJgM8zH/gqeIZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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