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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6d9f66d43b939d090a0f6cf8be7a9fd7bbb57423f3099424c0c03ae0be9eb89' 
  AND token = '9ABQEjaTSXYX4COpx0qqBXlRDDu+ZbqYIy8IEHd+jLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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