SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4b51582164576d09313f92995b83a7340dbccaecfacea8a2272cf5fdb1eff34' 
  AND token = 'pJZQWrcrv64TcuhlwbyWEnjAR/CBY32sOkLL+qnBrsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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