SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae474c43712ee5fd671e991e16bc0b4f067421957f38bf76f3b32890e16ad787' 
  AND token = 'RjuZGymYgbBedeV+ij772kAE/Rh8nzLbckR/FLjUOLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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