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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf208af8a9306237da1e50527feaa4ae2536a1851dc1cc3cb999bd96ee10c35a' 
  AND token = 'xQ5qV4WPsQBAWIMq8Dq+aE04h3AAwF4t5aDDXk3wlc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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