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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3b8943bd0d469b2b9c4a2036a4089d92df5aa61ad0e6ed70207121a26a19831' 
  AND token = 'mCM/aXA6LBi5ui4xflQ+E7dpLxK7Oxmp7ljJdL9BUbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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