SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '721b9bdb2ac9890449f0ecedba176b5f958466ffc986ecf124484d3123fb9258' 
  AND token = 'yDPszhNH/eZm3zC83KqoUR+FAeFjpAc1GJeguBfPiMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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