SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c777358ccdf25c180381bcdfcb5d238a6026dcb84e2c01ceebff9375774ed151' 
  AND token = '3uep+kSynfTsWh9y8k9ncvCzwox5YBP2dC2yXs/YMRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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