SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6b273a74c32a65afead460668347de096338491b6d3b63609889feb758381d' 
  AND token = 'hvf87rCQhXMWK++YmdVyWWLmDwQtstJj6MKFPrkIj24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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