SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a20edd351164142450056c5726a1a90c4e130a9b713bc59ec1134840fe0842' 
  AND token = 'l9EFmq61/jxDPOdxGsGKcbOzUqYemJZSFHkFxddHOVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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