SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5ea8df8f3f70ba9ab430ecb1646c54136c420c8b68050894fcf044db01d1b9a' 
  AND token = 'HHywW3fhNnOumcXmE4ohYkXpYTVoIeFStxt4rpkhGAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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