SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5b77bcf20c84b82e636a4485552cd6a94530eddbc35427be7156cb328f594fb' 
  AND token = 'YgIAgrFMApwVdQMD8KwW1tJT+KHbPfVWQg5Q0qJUCf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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