SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a632edd72b3b976e2a46fb310d081404a88b83e9c8655a3414c1487722fcf977' 
  AND token = 'z2D2FULPCBLwgtsOARlwPVOTbztos6Hu9+I7qC258jo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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