SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8899b702b500e1ff8d30d72e52d046973602621399a829b9f60878ec6ddfca17' 
  AND token = 'uezhajC1z4fYc7jhWGMyHaHgJfkFdoktkoOBDMtKgc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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