SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffdfbf67fc266a67b0128a8c2095bf418f17b3c243b0d33a068c9e7090b72576' 
  AND token = '6RdzSgYDlyRb5tBxqIzLJSAEV0K8IPmTGwdR7FWSkOU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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