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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'df77a21bb2a7bbf88c0c0f2efcb0494027f91d11d23ea8f35384d7a64aed8289' 
  AND token = 'ZTgYq0jqt5vfyqenqtj6yusKp8zboCfIwPi4O03Am74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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