SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b75ed43767e943bc62c568c7851632e6a300220425484cf6830caae4fa9f8d40' 
  AND token = 'BvfkOqrK1rAKovitOkmBs1xqTHiARzIz/k88CJRDmNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00064

JSON explain

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