SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38c5df392e41aa45093b536f841549529395548985bf5cbd4a1171ef0f6a7a5a' 
  AND token = 'Xy8LpsEl3DIH7GqBCJBQEy0sGlhv0yVqPtEa/9MOClI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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