SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '844ad2a7921aae9d397e25b3d37704a8f231821acaa04ff6ed98b11a7130be17' 
  AND token = 'qGqRJNnJod9ur1nHJUqmOngrnnNCJPmnuCiNIyih1m8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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