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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e9b3777e60cdaf2890ffd7b7edfd3d830dc8043ada36124c91a394d4b301363' 
  AND token = 'kNuzYTEMBHQ/ZzVdFeesZo+tE9w3aJtX7JFqQQBK3xQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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