SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73efc3d4451e3667fc581a1857d171e47b1363319f7f2bf0b276db504c15d458' 
  AND token = 'LU4+oI10/rs/ihsqwRLuVChjg/rJLVSzILuB2rVYSlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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