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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df2c3fd400c67e9f778a16eec6d711fb04dcb6e84bd662475d4f744d0776b6e0' 
  AND token = '8Hs2OOTCZxTh/x4/fjQ/wHQtVt8Ss5xEOfnGnSlxz80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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