SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1f76475cd46b1b75c9df5c3486bb9f3616a36831fb2b00423ce90979016828e' 
  AND token = '1MlMKzqJmAPiN7lVJR4XZjZfDutgpfqIrpaHLiMb0h8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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