SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '923c1c79538984b1d0875249ec37c91dd8f9da6bc3c3f15646ead08f2d64eb25' 
  AND token = '++6OVBK4JlFxxCXIng3Y0bSnTiIOC9C0RhQimqD9lHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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