SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba751aeb1a4a6ffb0024f11f96ae4cb06e6521e302417ae0051ca1d4435b0db1' 
  AND token = 'KpUepZZjU0UjKHiDnCe1SvY4vctWxVF6XHdto5aUBRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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