SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55267c8cba0f9a45e2a260ea42540670a441d95716effa8d89587461aadec6a2' 
  AND token = 'PziMjppUEBIKCZBqcxlHwg9uoGu4eERBjiAkVV5trTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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