SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bcff437065a118a6fa829e14d1c4631766303a531fd0fb8c57c0a282118efab' 
  AND token = 'ZeBVubLTemmCJmMR4cccX0+jzUa3aMRuWEJ0GKOTBvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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