SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9a02c5c2d6bf251616992a0451100a49a6d847137ced674997e129d34338ee7' 
  AND token = 'SbvA+4IuURcXTtvORLaRiR8N8jqLqfVjoFzPsV2M2mc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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