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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6fb80c0689abbe8d80c16eb1fd021b29d2588f8bc70a005dd2eed8cabd897fc' 
  AND token = 'xW/Xl38pvbeZbqQZiTnc+lqekSuhEiCTGEzWOCl4jvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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