SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f14a15f23a9c9eef2b1ba2c8029536d35606221b9445a1c805315f499d85bbb3' 
  AND token = 'RA4KHzg0TbPEcNWdZwvZDEOWIN5YwFT2hZBVsA+JghU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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