SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eaa3ffff797a04a3fa2bfced4e4fc019b9ee33c518952dd3e85cdee60ba0f925' 
  AND token = 'f11bUSLUbQSbklnm8AmQkJRN3wdrSCEnmXFVS0iKAhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}