SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd92321578ef8c92d66aca9bbe15601f30581fac783e24a6a8ca7f5382a43d921' 
  AND token = '5APOq9XjTcVrP+h8O0hI+MAhMgKWC4JqCLFIAPWJp5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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