SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9950446f6bad627f2fa486febd94266af2ace173350509fd216e8113c05ea1c5' 
  AND token = 'LYRqOLKD7Tc+PQwp3BVdpMmSoBwmsIdZ6jnaf7iypEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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