SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a6980d0bdbc491c3f5fa51a8f47c8ffdf280d83185d48063c550464ca551f82' 
  AND token = 'kXGHAbI7ijCPJhwXkTen+PhLi2EV0MaD0A1dznStQSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}