SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc490b1835bf88fa9a459d54314024d128dd377d88e41a2407004b8edbbc0336' 
  AND token = 'aiUR8gHdTywhRCttxXFjr5NsuWz96i3QCzYFDtQfVD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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