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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3550007670e0eb5178acd3012944da6864d6a7e904a6f44fa4192616261e4f39' 
  AND token = 'QajsfCXDFatbeXAO8G3VP/sQtXOtqkizhJxM216O9CI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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