SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '549d3d350d72fac4df688f1291e1799301cd98ded5ff6006f4f97eabed02760f' 
  AND token = 'XVrzRJSbv2u8RCvvpwnXkxKwRYHkamTloYjCukYYB+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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