SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31f30543368d36246a0f0e11c837356ae265779f9a7de031d0d47cec14c69444' 
  AND token = 'EP0wqtXX1893EeWa1CgNdtU/wc1BzPmMvqubamVoUI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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