SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fb7b8b9535ace593b7efca6fcdcdcbfd4da5f3750eac926e009d4fcc25452f0' 
  AND token = 'ZlQ8TvbMcruDgdLsOyCOni+fHnO1AnbQwPkMStAv8h4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}