SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50260e536f74d446b84335bd37e68a11d55b8944f1f4d7a5181c9ebac09fd205' 
  AND token = 'qOnTMhTfbeHV3pcnhpMKyGe6ult1wcAAGFglMKdPigY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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