SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f533c73eefb0644af9f7d03c9b726709fd86f5da8bd012afaa5473d642cdf32' 
  AND token = 'rwA3jTrtjD5Rzyf/axashhLVZJbvQsYao8RPGceRwC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}