SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfb55fce8eb86ec24f7161c177a62f82bd27a6207fad5d5d1c6305f65dba8267' 
  AND token = '3gmGUGxjZKPL6u5yGPmxwZZ9+5uSQH6u0l1+WCvshpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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