SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c6231e1111456967adaf1247ab4575e8375a5e5980418d1182d47d84a2af117' 
  AND token = 'qjjL4pvhzGcpIOkaHzvyXUGf8NHt2yXd5Qoji8E3+Zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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