SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbbd1e32832276f9016b2a3607237088b388376c6f5ebdb13c0afb7e45e9ea7d' 
  AND token = 'Oq6u7D6h5AGTM5+LbBw0mWIAdCuXmKWvgJ0VgSgDpo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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