SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54dfefb979afcdefb187b60af8539583968f9f9c6cefd226a5bc244f11c6527a' 
  AND token = 'F5jms4PEzmQVCjR3OYJ4FJTBt5YFpaiOK/36uTjd6G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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