SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75e5909a181bd4c2d2b50ab2b62dfb5c283063a78f70205aa92194daef11c23c' 
  AND token = 'it4mUIucJH92PR0uS4FWGj/ErS7VxBplY8r6qwKlbmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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