SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '679e1d0aaf79b0dc56158b4ef95bba66c27b4a608aa0efd5a0f743224cd0bba9' 
  AND token = 'gBjoGu9nJ5MntWQjJ96rXoRtfmTnVNyCDUD/OuKaHCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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