SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59d9fb32826324ba8ec515689b3bc8051697394acdbeecf64682d45fd20cca10' 
  AND token = 'JUD6sU5Qdfhpzma6UfrtZALH5uHWihwd69uoVIHjF0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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