SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4847ab387bc752a1729c794a36f822668b87a654ec5fce857f99246c421b9f6e' 
  AND token = '0/HjgMVVdYx6axUL9vJ+9UC2hM6mFVLmsADBcoZXgIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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