SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3839db2188e0a79c155dbdb6656a3c22d76fb12088d0365ef25972ba4ae917c0' 
  AND token = 'oXDCPK04UzRcIu9ajKxxMDRjirRwf1zz0C9eXiSpohs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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