SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc7d82fd0a9fc414e76fafc3fb5517a08ae396ef16bc9ddc341f170aac2eced6' 
  AND token = 'l3jZtPP+mNrzYgBWUHKHQhIVQPFklaTmTkZndXUMEwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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