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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b1d0a843a8e300cac36cc1b2b69fb5c7df394b994d8efd8832d78a1228f1c38' 
  AND token = 'SF269Mk4S9FI4HzOmIRaQPz79nQ9Y+V73B9FiW4ZSmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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