SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '842240984260fcaead00a4a5f4b46d0ee1aa70e3f43b89e6a685289eb3ff66a1' 
  AND token = 'E82AiX7lVKsUCayjDfRLVRjM5sqqUK5xsQ3OfaLnuoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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