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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e7c5154da211c9a16241ef809ada30a8207c7d55d4165fc65c54670597a6390' 
  AND token = '2GExXClOhjAx6iyLzGPrb+d2zFpOt9xzRr4uanJd200=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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