SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a252fc83e3f45dc353ccd3d5967857ce6cb03bab2bd492acf0fdb30122f88bea' 
  AND token = 'Ksa/OcYBCA1AbFUXfAYsPhslb8n7pck59nwfeTXrRy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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