SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a689485701804122b132f7027941fbf480423a32a7b9d168087e66f586fa830' 
  AND token = 'unFxX6l3MwsC+BLb/Pi2GCmfEJ53P/nqjjOStxKVLFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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