SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffa7ebd983b840d7410ab1d4732216e3bd606daaf6f98a85dfb11e291dd5f680' 
  AND token = 'wsK9JfUBrR4D8soJYI1pVKH9HVzmNciWoZt/h28ZaPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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