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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c57b1ef2f89b157cbcc07714ab2cad4dfee2af3d779466d01b70311a75c63d1' 
  AND token = 'PO/zECkRYIkBZsSfZgIaEVAZjT3ABi7WA/93FkFb/kQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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