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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a6608aa3674f02dac6940bc0181b657aa0f7b1529ebf94e71ed8667e658ced7f' 
  AND token = '52xQj4Km0ViWQ/hST/TN7kTEWus+9jrlX7OId+bNFYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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