SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85d600556966972f6ed10d2a793fd65b92a5f923c1d83c5617a917fe42593251' 
  AND token = 'vR8UrF51VId+lf9T0IJ69VeT00KwAKwR9sIXO6st/HM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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