SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a604430f41ec5d0e1bb279b884c087704bedcc386405a2e554b4ba7a810e389c' 
  AND token = 'Z3KQ3RnsFfGqVDjMc9v98D+/Wo1ENy7BEtvDZk1kMto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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