SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b151f7e683c61d730eede503429f89116301791ba826d2f2906a10037157b2a' 
  AND token = 'MUmX1PrrbAsmE7jW1wWp+KbcKdSUpo9tR3auH724kqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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