SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5761c46cffddaf09f33ce55e25e1cd9af9d3c2126e5dc1f6b94f366ddd072e2' 
  AND token = '9xnWEKm0mN3wTYfi1Q/uJu4BYWj/n52utsCK8bTjYMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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