SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc7b07e90c6cb20afe4fc6836627b7624e1c98f828c2d07193a36d3afb4c0b35' 
  AND token = 'O/dtyT/aE3WWRyOhVn7+7NVUVTlCIXGHaubAmaCwWTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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