SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fcea504f7fc1bfacc56ba8f2473e06aef54103442000d74eba8307be87ec51f' 
  AND token = 'Uk/tq37IcdMrjZbRbWVKPvvEjXyNtyjcX5cNfO392A0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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