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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17392dac96b2fe6a9059853899aa5f80ac35c9fa556a5aa67338eacd5462dc7c' 
  AND token = 'a9zkpvKJdxxD5LqgF+YqWIjpCkzFO0+TMD1egvEstN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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