SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b498199976b952608aeccf40801fd2992f129830c5276de2ec3f25f02e671f7' 
  AND token = 'oH4UZ21wY2bJ9/sOGtlBTkrqIVSaaN9GR3gOzljZ5Rs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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