SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5976382ea31560c4608f7599fc2fc88206e824dc50332d6f0ad194f9aac06010' 
  AND token = 'w+x9FmYqBvUrbYl7NGvZgHO6ZjG7d44RMtwvdBhxjHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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