SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de377e4f08137111509f23c17173e5346f83ebc7274b123de1ad969b37381a16' 
  AND token = 'hA6lOum1kMcOVD4X4otvalMK+U9gBNgcR+AAnGlhWIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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