SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f15368eb4df39eb7c2c872af6e68abf711875f4f578333c5e4e6d8fca806e35c' 
  AND token = 'MbVfE+6w0mMQHNzaDw3gSI73p9csy6V1F/gFwVnMy/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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