SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7bbff2168c01dfcbfa35c57bdf26c5c26f0d5e41c1d8eb9f87d2f43fbbf7a13' 
  AND token = 'K+aQTlaqWe4/d8jXjtflyGBQIQHvqLycTJXnKp5HZRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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