SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e988de3c02e2490ee552fd2dbeaa2c66171141359ee6d75062af11f157cabae' 
  AND token = 'ApEl7o0UFmp+e0zBzc9magCpKIOwqwLgfFDDLqDPc7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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