SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '638d00b9fc7e346a0fd274ae3c28702ff371b2aec82cc622fdd8746b501b4845' 
  AND token = 'mkjzv3K0xssJJgCV+vRaSK6GwVFrj5650fS87CngHWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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