SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8215bb0468c9e602a1c4d3596a38df620d0ad0fb73f7e414b47c5040c5cb7cc' 
  AND token = '56zQLVO55NR+JRKJBs9688OYeAJKj65niAGRjj6Jv38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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