SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b796c537272b369ad71cbded55667cc1b4387de5d7dfbdd950248db7c28b051' 
  AND token = 'UBC0XXxBRiI/mHePwwZVcQgwPwLqCnpcmI5ltN5454Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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