SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b892bc557e14b146d5151bb0c42647fab2c3da05daf6a95263cf8755076273ce' 
  AND token = 'MHCeTIL9SVnylTwzJiUmOaaM4qeAAgnfXvyLWS6F0+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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