SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712c4a76ce112277a38c2bb00e5a359c08a5773061360bc0fba39522053687dd' 
  AND token = 'XdVDN/5sQqTWKzuprPOnkjOk3HP69QQBAU7/VewfIRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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