SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa82d5c83a99b26a9484acbe482cd1c5a578a28ac13999903877eb007a6289e8' 
  AND token = 'BLAnUeXSw8wmXkn76lukSIYTL9IAPCyvPwUzWuPlapk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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