SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a998d18cf47087ae42364b93a56bfae701005945fd6c89a5e5962ec79f722e2c' 
  AND token = 'RmYT+UnWWL57gPwytn32CSujdHH9azIP/+6AezMTTAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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