SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbe1561f25987b534888f94abdbbb724bfa6ce8975bfcf0d9c3434b42033363c' 
  AND token = '9tsdnsg6wr6YvssaRj81rfQpiw5eCUsyWlsZWNSVTAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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