SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '989d4a61b1dc2d6d486b94fe57d12193763654b2c1b056ed2a1f15a4a9519766' 
  AND token = '3gLuLl20y3CZcLWTLQWLYzSunNE4/EmpqmGHeI/KXBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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