SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6082a56159ebcb1c5d5e490d66aa8c01ec2a7391adcfb27d625c241199462d77' 
  AND token = 'txrBJ/f1Pwp5uWpjPkCrp7kyUqZUkYeKGvCJcnrWV28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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