SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fccd5a9027a6d0f6ac8ea549ef851a2ef620588de0ce80673c319ad46f3f667' 
  AND token = '8LRJB5UKcyHj+y6KYGZwyQzgPoVkaaqvMTau0VwdiFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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